Hello Friends. If you remember in 2014, director Christopher Nolan’s big blockbuster film Interstellar was released. In this film, space-related concepts of wormholes, Blackholes, and alien planets were all shown in a very scientifically accurate manner.
Gargantua black hole:
But perhaps the most horrific scene was at the end of this film. In the Climax the main character of the film Cooper falls inside a blackholes . The name of this black hole is told in the film Gargantua, Cooper falls inside the black hole with his spacecraft.
In the beginning, everything around them is pitch black, complete darkness. But as they fall further inside, some grain-like particles are visible in front of them. These particles come to their spacecraft and start scratching them. Some flashes of light, some sparks appear and fire starts in their spacecraft.
They are forced to eject from their spacecraft and they keep falling inside the black hole, but then suddenly they find themselves inside a 5-dimensional space. Is a 5-dimensional tesseract. This is very mind-boggling stuff. There is a place where they can communicate with their past, using gravity.
Seeing all this, a big question must have arisen in your mind. Is all this possible? Does anything like this happen inside a black hole? Let’s try to understand all these questions in today’s blog.
What will we see if we fall inside a black hole?
Friends, let’s start the story from the beginning. The history of blackholes is not very old. 100 years ago no one even knew about black holes. It was only because of Einstein’s theory of relativity that black holes were discovered later.
There are two parts to this theory, friends. The special theory of relativity or the general theory of relativity. The special theory of relativity, which Einstein published in 1905, tells us how speed influences time.
If you are sitting in a spaceship which is flying very fast. If your speed is very high then time will move slowly for you. Relative 2: Those people who are not sitting in the spaceship are on the earth. The word relative is very important because when you are sitting in a spaceship, you will not feel that time is moving very slowly.
Time for you will be running at the same speed as it normally runs. Only if you go back to earth then you will realize how different time was going on.
This thing is called kinematic time dilation. Now time dilation can occur not only due to speed but also due to gravity, which Einstein described in his general theory of relativity. He had developed this in the year 1915. blackholes.
The more you experience gravitational force, the more time will slow down for you. This is called gravitational time dilation and was shown well in the film Interstellar. When Cooper and his companions land on an Aqua planet. For them on that planet, one hour is equal to seven years on Earth.
This happens on this planet because this planet is very close to the Gargantua blackholes, so the gravitational force coming from the black hole impacts it. Now, to visualize this thing, Einstein had said to imagine a fabric of spacetime, imagine a kind of mesh on which all the planetary objects are placed.
The more mass they have, the more they are bending the mesh of this space-time downwards and when this mesh is starting to bend, not only physical objects are getting more attracted towards it but also time is starting to dilate from the middle.
And other forms of energy like sound, heat, and light are also affected by gravity.
Heard right my friend, this was another conclusion that Einstein had drawn. Gravitation affects almost everything. Not only physical objects are attracted by the force of gravity, but heat, sound, and light are also attracted.
So, friends, this means that there can be such objects in the universe in which the gravitational force is so much, so much That they absorb the light completely inside themselves and if there are such objects then it means that they will be completely black.
We will not be able to see them because even light will not be able to come out of them. Exactly this is what blackholes are. But when Einstein told his theory of general relativity, at that time the concept of blackholes was only theoretical. Einstein knew that gravity influences light and theoretically, there can be objects that can observe light.
But Einstein did not know that black holes actually exist. In fact, till Einstein was alive, he found this concept of blackholes very strange. He knew that theoretically, such things could happen but he felt that theoretically, things like infinity could also happen.
But realistically practically he was not sure that such things existed in real. So actually the word blackholes was not even invented till his death. Here is an interesting fun fact: The key point in Einstein’s theory was that the speed of light limits the influence of gravity.
It is not that we feel the force of gravity instantly everywhere. Its upper limited speed of light. If I explain with a practical example, it means that suppose the sun suddenly disappeared.
You all must know that only after eight minutes we will feel that the sun has disappeared on the earth because light takes eight minutes to reach the earth. However, according to Einstein, the disappearance of the sun will have a gravity effect on the Earth.
We will also feel this only after eight minutes. Isn’t it a very interesting thing, friends, after Einstein, which was the theory of general relativity? Many other scientists worked on this. Like Karl Schwarzschild, Johannes Droste, and Subramaniam Chandrashekar, there were many equations,
These people solved those equations and tried to find their solutions and by finding the solutions of these equations it was possible to theoretically prove that things like black holes exist. By 1960, finally, researchers and scientists accepted that not only theoretically, but perhaps one day we would also be able to see blackholes realistically because these things actually existed in space.
The term blackholes was first used by a magazine in the year 1964. But this word became popular only after the year 1967. When physicist John Wheeler popularized it. Although the word blackholes sounds quite sensational, it is a bit misleading.
After listening you will feel that there is actually a hole there. But this does not happen. There is no hole in space. Blackholes are made from stars. So there is definitely some material in their center. Now friends, what happens in the stars?
As the Sun is also one of our stars, nuclear fusion reactions keep happening on its surface. Due to these reactions heat and light are produced. The heat that is being produced exerts a force on the outside and the force on the inside of the stars comes due to gravity due to which the stars stay alive by gathering together.
So in a way, every star maintains an equilibrium in his life. Outward forces due to reaction and inward forces due to gravitational force. But this reaction which is starting to happen, it is starting to happen due to some fuel, hydrogen, or helium. This fuel will not last forever.
This fuel will end someday. And when this fuel runs out, the force which is going outward will not remain. If there is no force left to counter the force of gravity inside, then it will collapse on itself in its own gravity. blackholes.
It will take a very long time for this to happen, although the life of our own sun is around 10 billion years. But what happens next depends on the mass of that star. Here we see a chart of the life cycle of a star. If the mass of the star is not much, it is small If it is an average size star then it turns into a red giant. blackholes.
After that, it can become a planetary nebula or a white dwarf. But if it’s a bigger star, a more massive star, when it runs out of fuel it cools down and becomes a red supergiant and then that supergiant explodes and becomes a supernova.
After that, a very small core remains. If that core is too small then it is called a neutron star and if it is a little bigger then we call it a blackholes. Basically, it can be said that the mass that was in a star when it got compressed due to its gravitational force, became smaller and condensed, then it can become a black hole.
Specifically, into what small volume does this material get compressed? If a black hole is formed in a star as big as our sun, then the diameter of that black hole will be only 50 kilometers. You can imagine the volume gets reduced so much.
But the interesting thing here is that our son will never become a black hole when he grows up. This thing was proved by an Indian American astrophysicist Subramaniam Chandra Shekhar who derived a Chandra Shekhar limit value.
He said that the maximum mass of a White dwarf can be 1.4 times the mass of our son. He will not be able to remain stable on that. Then it will go to a neutron star or black hole. But because our son is below this limit, he will become a white dwarf, not a black hole.
The Stellar black hole:
Now that you have understood why blackholes exist? Now let us understand what a black hole is like. Friends, there are mainly three to four types of black holes, the first one is a Stellar blackholes. Which is the most common type of black hole.
Those black holes are formed from stars. Scientists estimate that there are at least 10 million to 1 billion such black holes in our Milky Way galaxy.
The Primordial black holes:
Apart from this, there are primordial blackholes. These are those black holes that are as small as an atom.
But their weight and their mass are as big as a hill. So even this is also an assumption that their size is as small as an atom. These black hole friends are just theoretical, hypothetical. We don’t know much about them.
Supermassive black holes most powerful objects in the universe?
The third type is supermassive blackholes of blackholes.
There are very big black holes. So big that their mass is more than the combined mass of 1 million suns and it will be such a big ball fit that the diameter of that ball is as big as our solar system. Scientists believe that there is a supermassive blackholes in the middle of every big galaxy.
The supermassive blackholes in the middle of our Milky Way galaxy have been named Sagittarius A and the black hole shown in the film Interstellar is a Gargantua.
The name he has given is also a supermassive blackholes. Apart from this, scientist believes that there can also be a fourth type of black hole, Perhaps it cannot be said for sure, but this fourth type of black hole will be an intermediate black hole, which is somewhere between the size of Stellar blackholes and supermassive blackholes.
Yes, although no proof of this has been discovered yet. So one thing that you might have seen in the film Interstellar and the photos you have seen so far, you would have understood that a black hole is not a big black ball that sucks everything inside itself.
Blackholes look something like this. So the first thing you will notice in this photo is an orange colored ring which is starting to form around this black hole. This is called the Accretion disc and it is a very important feature of black holes.
Now as you know, the gravitational force is very high in black holes, so due to gravity, a lot of gaseous matter and the rest of the debris is attracted towards the blackhole and floats around it. Like the rest of the planets revolve around our sun because the gravitational force of the sun is so high.
The difference here is that the gravitational force has become so great that the things that are starting to rotate around it are starting to rotate very fast. So much heat has gone up that everything has become a flowing fluid-like matter.
There are particles of fire that are hotter than a million degrees Celsius. The closer you get to the black hole, the faster these particles will be revolving around it. These particles rotate so fast and rub with each other, that compression happens that they start to glow.
Electromagnetic radiation starts emanating from them which are mainly X-rays. So this accretion disc has been shown very accurately in the movie. Only one thing has been wrongly shown it is not actually of orange colour. Human eyes cannot see X-rays.
X-rays are outside the spectrum of visible light. We just represent it by giving it orange orange-yellowish color so that we can show that there is something here. The original color of this disc will be closer to blue.
For the first time in the year 2019, a photo of a black hole was taken and in this also they used this yellowish orange color to represent this Accretion Disk. Now one thing that you can notice in the real photo, which you may not notice so much in the movie, is that on one side these particles appear to be of more bright color in comparison to the other side.
There is a very simple reason behind this, the particles that are spinning toward us appear brighter in color and the particles that are spinning away from us appear dim.
This happens because of the Doppler beaming effect. So when you see the real photo of this black hole, then by looking at this blurry photo, you can understand in which direction these particles are moving. The brighter place is starting to come towards us and the dim place is starting to move away from us.
Now coming back to the movie image, you will notice one more thing, Accretion Disk gives a kind of optical illusion due to gravity. Looking at it, it seems that this disc has covered the top and bottom of the black hole. We see this only because gravity is beginning to bend the light.
The part of the disc which is hidden behind the black hole, when we are starting to see it from the front The light that is coming out from there comes from above it and gets bent so much because of gravity. If we look at black holes from the top view, they will appear completely round, they will appear like discs in a normal manner.
We see this illusion only when we look at black holes from the side. Apart from this, if you go inside the black holes, you will only see a circle of light. This is called photon fear. The village has become so strong in this area that the light itself has started orbiting around the black hole.
From what is light made of, it is made from photons, so these photons have started going round and round around black holes.
This means that if you reach this area and remain alive in the black hole, then it is theoretically possible that you can see the back part of your cup because the light is going round and round in the formation of this ring.
After this point comes the boundary of the black hole, which we call the event horizon. It is considered a boundary because after this point gravity has become so strong that even light is not able to escape, that is, everything is black. All that is visible is black.
You are falling inside a black hole and you have crossed the event horizon, so theoretically, there is no chance of your escape because even if there is no light, a person can escape. What can escape?
Now it is shown in the film Interstellar that Cooper’s spacecraft keeps going inside the black hole. This event crosses the horizon and after that suddenly they are in 5 dimensional space. This part of the movie is purely imagination, and speculation because we do not know what will happen inside the event horizon.
The producers of the Interstellar movie hired a Nobel prize-winning physicist to keep everything scientifically accurate. But, for the things even science does not know, the movie has used imagination for the things which we do not even know about.
What will happen in the center inside a black hole?
Einstein’s general theory of relativity tries to describe it.
This theory has called the place in the center of the black hole a singularity. Singularity is such a region of a black hole, it is the center where the curvature of space-time becomes infinite.
Remember the mesh that I told at the beginning of the video the heavier an object is, the more that mesh will bend the spacetime. In the case of a black hole, this bending becomes so much that it goes to infinite bending because we know from the theory of relativity that gravity affects all things of time and energy.
when will a black hole hit earth?
If the gravitational force is so high, then time also goes on slowing down infinitely, but what is the meaning of time being infinitely slow here? Does this mean that if you go inside the black hole and can never get out of it, then the universe would have ended for the outside world?
We do not know all this, actually only theories can be made. What do you think here? You can tell by writing in the comments below. Some very interesting theories are suggested here. Just as we cannot see inside a black hole from outside, all the light is being absorbed inside it.
However, one theory says that light is reflected from many places inside the event horizon and reaches the singularity. So it is possible that we can see things inside the event horizon. The thing that humans have seen for sure to date about black holes is just this photo. Photo taken by Event Horizon telescope on 10th April 2019.
Which practically proved the existence of black holes. Many 100 years later they were proved theoretically.
Now one thing is sure here if you fall inside a black hole, then there is a chance that you will break into pieces due to gravitational force. You will be killed within milliseconds but still friends, there is no need to be so afraid of black holes.
Many people had this misconception earlier that black holes keep sucking up all the matter and keep getting bigger and eventually it will destroy the whole universe, but nothing like this happens. As I told you, there is a supermassive black hole in the center of every galaxy.
All other planetary bodies and stars which are in the gravitational range of that black hole revolve around it. In the same way, all the planets revolve around the sun in our solar system. The same thing happens more powerfully in the middle of the galaxy.
So in conclusion, if you keep a proper distance from the black hole, you will maintain social distancing. So will be safe and secure and the concept of 5 dimensions that was talked about in the Interstellar film is also very interesting.
Let’s talk about that in some future video. For now, if you like this video, then you can watch more space-related videos. Thank you very much.